Nominal standard dose and the ret

Abstract

1. The criticisms adduced by Liversage of the N.S.D. concept and the Ellis formula are based on misunderstanding and insufficient consideration of the basic reasoning and evidence. 2. In clinical practice, by providing a single figure representing biological effectiveness, the concept and the formula are useful for teaching and comparison of treatment schedules besides being safe for prescribing. 3. Virtual coincidence of isoeffect values for normal tissue (N.S.D.) (Table I) and for Hodgkin's disease (tumour S.D.) (Table V) support the concept and the formula. For most other tumours the tumour effect is incidental to normal tissue tolerance. 4. Optimum schedules for various types of tumour might be possible to derive when more is known of the mitotic cycle times of the affected normal and malignant cells underradiation treatment. 5. Continual testing and sifting of data are desirable to verify the concept and to adjust the exponents of the formula.